
The do file to use in order to obtain patent citation flows that proxy for knowledge spillovers is:

"PatentCitationsFlowsConstruction_ProbMapping_SOM_RESTAT.do" (Stata do file)


This do file uses data on patent citations to construct citations flows to proxy for knowledge spillovers.
Patents data were purchased by the LSE Department of Geography and Environment for projects related to knowledge diffusion.
The data cannot be shared but can be obtained from CESPRI at Bocconi University.

The do file maps technology classes onto industrial sectors using a probabilistic mapping based on the "sector/industry of manufacture" (hence SOM in the do file name).

The mapping between technology and sector of manufacture was originally created by Silverman and can be accessed via the internet. 
More information is contained in the Web Appendix of this manuscript. 
Note that Silverman's maps technology categories to Canadian SIC. We further mapped Canadian SIC to UK SIC industrial sectors.

An alternative mapping based on the "industry of use" (IOU) can be used. This was also worked out by Silverman and can be accessed through his website. We use this alternative mapping in some extensions.
Producing IOU knowledge flows simply requires loading different data provided by Silverman in the do file.

The initial calculations were done with the following restrictions:
- Drop citing patents after (>) 2000 and before (<) 1987 + drop cited patents after 1997

These restrictions were extended/modified to include the following periods:
- Drop citing patents after (>) 2008 and before (<) 1981 + drop cited patents after 2005

The files have been saved with different extensions. Files ending with _08 cover the extended period coming up to 2008.

The main file created as final output for the shorter period is called:
-pat_citations_EPO_coagglomeration_prob_SOM.dta

NOTE:
When labelled with a _08 extension, this refers to an extended period of time. 
When the _SOM is dropped from the file, this refers to the alternative IOU mapping.
